During a drilling process of petroleum and natural gas, calculation and control for the wellbore pressure become very important in order to avoid complicated accidents such as leakage, kick, hole instability, sticking, and/or the like. Currently, a gas-liquid two-phase flow theory is one of theoretical bases of gas-liquid two-phase flow simulated calculation for the wellbore, which establishes a gas-liquid two-phase continuity equation, a momentum equation by dividing different flow patterns, to simulate a flow state. However, differences between different calculation methods are relatively large and thus the precision is hard to meet requirements for calculation of dynamic pressure of a delicate controlled pressure wellbore for pressure sensitive formation.
To avoid the occurrence of the accidents, the drilling method for managed pressure drilling (MPD) has been widely used in the field of drilling petroleum and natural gas. However, there is no solution for a real-time control of the MPD pressure yet to satisfy the requirements for fast and accurate calculation of the dynamic pressure of the wellbore for petroleum and natural gas.